We propose to develop a novel non-surgical technique that will allow us to reintroduce embryos and blastocysts into pseudopregnant female mice. This technology is based on methods that were published a number of years ago and involves the introduction of cells into the uterus by way of the vagina. These earlier methods used glass pipets to introduce blastocysts; we have developed a novel plastic device, which can be used with a P-2 pipetman, to introduce embryos and blastocysts intravaginally into female mice. This procedure takes several seconds and the pain and discomfort level is minimal so the females do not have to be anesthetized. [unreadable] We have generated some preliminary data and have shown that we can introduce embryos with an efficiency that is comparable to surgical transfer into the oviduct. We have also shown that we can use this technique with embryo aggregates to generate chimeric mice. Thus, this novel technology should be able to replace surgical techniques used for the production of genetically altered mice via DNA microinjection and ES-cell mediated gene knock-outs. We believe that this is a dramatic improvement over current methods, and would become adopted as the method of choice for transgenic researchers if it is truly as successful as our preliminary data suggests. [unreadable] [unreadable]